[SOLVED] read weighing scale data via RS232 to USB cable in python

Issue

I am trying to read data from weighing scale YH-T7E using raspberry pi via RS232 to USB cable in pyhon. However, when I am reading the data via it gives me empty string.

Here is my code:

import serial
import time
ser = serial.Serial('/dev/ttyUSB0',
                    baudrate=9600,
                    parity=serial.PARITY_EVEN, 
                    stopbits=serial.STOPBITS_ONE,
                    bytesize=serial.SEVENBITS,
                    timeout = 1)

while True:
    print(ser.read())

The output of above code is:

b''

I have also tried solution from this post but it gives nothing since it keeps on waiting:

while True:
    data = ''
    while ser.inWaiting() > 0:
    data += ser.read()
    if data:
        print("Received: ", data)

I have verified RS232 is properly connected with the laptop:

[ 6105.752153] usb 1-1.2: ch341-uart converter now attached to ttyUSB1

Even when I used minicom, configured baud rate and other parameters, still no data received.

Here is the YH-T7E manual for the reference

Kindly assist me?

Solution

Your code looks fine. The call to ser.read() would read one byte at the time - so you should see one character per line if it receives any data. You should probably troubleshoot a bit here.

• Are you wires connected correctly? Is the TX from the scale connected to the RX on your RS232 port? Are the grounds connected together?

• Are the communication settings correct? Have you tried to set it to 8 bits instead? Also try to set parity to ODD or EVEN, maybe NONE also?

• Does you USB RS232 work? Maybe you could check it on some other device?

Answered By - J. P. Petersen